Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
Generally, an image forming apparatus, which employs an electrophotographic method, such as a printer, a multi-functional peripheral, a copier, and a facsimile, includes a fixing unit for fixing a toner image by applying heat and pressure to the toner image formed on a paper sheet. The fixing unit includes a heater to heat the toner image. The fixing unit includes a sensor to detect a temperature of a fixing member, which is heated by the heater and fixes the toner image on the paper sheet. There is provided an image forming apparatus that detects disconnection of the sensor based on an output from the sensor after electric power is supplied to the heater for a certain period of time when the power supply switch is turned on. Here, if the image forming apparatus is turned off and on in a short time, electric power is repeatedly supplied to the heater for detection of disconnection, excessive temperature rise of the fixing member may occur.
One technique to avoid this excessive temperature rise of the fixing member is proposed. Specifically, there is known an image forming apparatus that includes a prohibiting unit that prohibits supplying electric power from a power source to a heating body for a predetermined period in the case where the electric power from the power supply to the heating body is cut off and then the electric power is supplied again, time length of a heating stop state, which is from the cutoff of electric power to re-supply of electric power, is equal to or less than a predetermined time length, and an abnormality detection of the heating body and/or a temperature sensor is stored in a storage unit. This configuration can prevent excessive temperature rise or similar problems of the heating body due to disconnection, contact failure, or similar causes of the temperature sensor and/or the heating body.